[devote]

var k, i, total_m, total_l ,
    boxes = [
      ['A', 'B', 'C', 'D'],
      ['F', 'G', 'H', 'J'],
      ['K', 'L', 'M', 'N', 'O', 'P', 'R', 'S', 'T']
    ];

for( k = 0; k < boxes.length; k++ ) {
    total_m = 0;
    total_l = 0;
    for( i = 0; i < boxes[ k ].length; i++ ) {
        total_m += parseFloat(document.getElementById("input" + boxes[ k ][ i ]).value.replace(/,/, '.')) || 0;
        total_l += parseFloat(document.getElementById("output" + boxes[ k ][ i ]).value.replace(/,/, '.')) || 0;
    }
    document.getElementById("total_box" + k + "_m").value = total_m;
    document.getElementById("total_box" + k + "_l").value = total_l;
}

<input id="total_box0_m" size="8"/>
<input id="total_box0_l" size="8"/>

<input id="total_box1_m" size="8"/>
<input id="total_box1_l" size="8"/>

<input id="total_box2_m" size="8"/>
<input id="total_box2_l" size="8"/>